User:GNUtoo/X60 GPU init

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Native GPU init

With the native (intel) GPU initialisation, coreboot itself initialises the GPU.

Initialisation method Free software, based on Advantages Drawbacks
non-free VGA option rom No, extracted from the BIOS.
  • compatible with everything
  • works with the official coreboot.
  • non-free
  • even yabel cannot contain it
Linux kernel i915 driver Yes, in the linux kernel
  • works with the official coreboot.
  • The screen content is only visible after the i915, so you cannot see grub.
  • It worked with trisquel6 kernel, and had issues with some recent kernels.
    • TODO: investigate the memory_corruption_check kernel parameter.
Native GPU initialisation (by coreboot) Yes, based on a replay of the kernel initialisation
  • compatible payloads can use the screen.
  • not in the official coreboot yet.
  • only compatible payload will be able to use the screen, like:
    • libpayload based payloads
    • recent grub versions

Related historic git trees

I often contained work on the following topics:

  • Native GPU init for i945
  • The fallback mecanism
  • The removal of the microcode

So I often have cherry-picked patches from gerrit and have some updated copies of some of them. The microcode removal is probably not in gerrit because it won't be accepted as-is, instead the microcodes have to be moved/removed in a cleaner way for master

Native X60 GPU init stuff

scripts to help getting rid of the vbios of the x60

Script 1: generate the io access for the coreboot driver

#!/usr/local/plan9/bin/rc

by the following line:

#!/opt/plan9/bin/rc
  • create the ssamfix file with:
 ,s/\[ *[0-9]+\..[0-9]+\]//g
 ,s/^ *//g
y/^[RWU]/s/^/M /g
 ,s/\nU/ ;;;UDELAY/g
 ,|uniq -c
 ,s/^ *//g
 ,s/(^[0-9]+) ([MRW])/\2 \1/g
 ,s/"/\\"/g
 ,s/^M ([0-9]+) *(\[.*)/{M, \1, "\2"},/g
 ,s/^M ([0-9]+) *(.*)/{M, \1, "\2"},/g
 ,s/:  */:/g
 ,s/...UDELAY *([0-9]+)/\1/g
 ,s/^([RW]) ([0-9]+) (.*):0x([0-9a-f]+)(.*)/{\1, \2, "", \3, 0x\4, \5},/g
  • run the following commands:
. /etc/profile.d/plan9.sh
cat dmesg| ./ssam  -f ssamfix > foo.c

Script2: compare the io access that were too fast

  • Replace {V,0,}, with {V,7,}, in src/mainboard/vendor/device/i915io.c
  • cat /dev/ttyUSB0 > accesses.txt
  • Use that script against accesses.txt to find the guilty accesses:
#!/usr/bin/env python2
import sys,re
 
def main(args):
	try:
		f = open(args[1],'ro')
	except:
		print args[0], " <file>"

	for line in f:
		if re.match("0x[0-9]*: Got .*, expect .*",line):
			line = line.replace('\r\n',).replace(", expect ",':').replace(": Got ",':')
			split = line.split(':')
			#print split
			if split[1] != split[2]:
				print line
if __name__ == '__main__':
	main(sys.argv)

How to get semantic IOs

In i915tool:

  • import your IOs in prettyregs.c
  • compile prettyregs.c
  • run prettyregs

How to get rid of the vbios of the x60 [New Version]

WARNING: DO NOT ATTEMPT TO DO THAT WITHOUT A FLASH RECOVERY MECANISM

Apply the coreboot patches, and adapt them for your mainboard

Then configure coreboot with:

[*] Output verbose x86emu debug messages
[ ]   Trace JMP/RETF
[ ]   Trace all opcodes
[ ]   Log Plug&Play accesses
[ ]   Log Disk I/O
[ ]   Log PMM
[ ]   Debug VESA BIOS Extensions
[ ]   Redirect INT10 output to console
[ ]   Log intXX calls
[ ]   Log special memory accesses
[ ]   Log all memory accesses
[*]   Log IO accesses

Build and flash coreboot.

git clone my fork of the i915tool until the code is merged in the official i915tool.

Get the tarball that contains the generated code, extract it.

Also get the i915_regs.h.gz file, decompress it and put it in final/

Then go into i915tool and apply some patches for the x60 or redo them for your mainboard.

Run make:

$ cd i915tool
$ make

Then go into the x60 directory(or the directory of your device):

$ cd x60

use picocom -b 115200 /dev/ttyUSB0 or stty to set the bauds of the Serial port. Then get logs:

$ cat /dev/ttyUSB0 | tee coreboot.log

Then remove the binary symbols, dos2unix will help identifying where they are:

$ dos2unix coreboot.log 
dos2unix: Binary symbol found at line 136332
dos2unix: Skipping binary file coreboot.log

Then do:

$ dos2unix coreboot.log

Then remove the lines before and after the log, the log looks like that:

[0047229e]c000:51cb outl(0x80001014, 0x0cf8)
[0047325f]c000:51d4 inw(0x0cfc) = 0x50a1

Then run make and fix the errors:

$ make

Then copy to coreboot as it says. Then if necessary try to compact the source code a bit, here for me I have a really long list of:

io_i915_write32(0xcffbe001,0x8001);
io_i915_write32(0xcffbe001,0x8005);
io_i915_write32(0xcffbe001,0x8009);
io_i915_write32(0xcffbe001,0x800d);
io_i915_write32(0xcffbe001,0x8011);

That can be replaced with:

int i = 0;
for (i=0x8001;i<0x3fffa;i+=4){
io_i915_write32(0xcffbe001,i);
}

Import the final code into the chromium fork of coreboot with my patches on top.